A wide variety of belt tensioners are disclosed in the prior art classified in Class 198. Gravometric feeders such as the feeder disclosed in U.S. Pat. No. 3,679,010 require a constant belt tensioner since a change in belt tension will create an error when weighing flowable masses on the belt.
The present invention satisfies a long sought after need in the art, namely a simple inexpensive constant belt tensioner which is reliable and is arranged in a manner so as to magnify or multiply the tensioning force. Such magnification or multiplication, for example, is not obtained where a weight is applied through a simple pulley.